You probably can't damage using group.

Strong is weapon, plus *character bonuses*, plus oils, plus variable damage (increasing with skill), less the beast's toughness, or reduced by it's armour %
Fast is weapon, plus *character bonuses*, plus oils, plus 1 damage, less toughness or reduced by armour%
Group is weapon, plus *character bonuses*, plus oils, less 6 damage, less toughness or reduced by armour%.

At this stage you only have the witcher steel blade (no damage bonus to silver sensitive creatures, no oils etc).
I can't recall what possible enhancements you can have added, but they are generally fairly weak.

If you have Strong 1, Strength 1:
Damage = 2+1+13(-10)-5 {Strong, Str, Sword, (steel vs monster), toughness ~ which is barely enough to damage - with 53 HP each, you will probably die before you prevail... final repeated attack gets +1 damage, but that is still only 6 per 'double' sequence.

With Strong 2, Crushing Blow (on both Strong 1 and Strong 2):
Damage = 3+2+1+13(-10)-5 {Strong, Crushing Blow, Str, (steel vs monster), toughness
8 in the first sequence, 12 in the second, 15 in the final. Two cycles will kill one monster. To stay alive you need to potion up, use AARD, and not get caught by multiple attackers from several directions... not too hard though - especially since the during initial fight you have the guards acting as distractions.

If you instead used Fast: Fast 1. Strength 1:
Damage = 1+1+13(-10)-5 ~ 0, so only 2 damage in a "double" sequence... possibly.

Fast 2, Strength 1:
Damage = 1+1+13(-10)-5 ~ still only 0, but 4 damage in a double sequence ... possibly.

Until you get stronger, have better swords, more armoured enemies (scales/metal armour, rather than leather/hide) skip Fast. It is slightly useful with pain, to break up attacking groups of susceptible enemies.

Group is good at this stage for staying alive while signs regen, as it maximises dodging abilities, but it is never "the best" solution for rapid dispatch of enemies. Fear causes enemies to run away instead of attacking once added.

I went with a swordsman build, as that is the "Lore" build for Geralt... if you spent your earliest points on other things you might have inadvertently made this fight far more difficult. I'd consider restarting the prologue with maximising early swordsmanship/damage skills as a priority. There are very helpful enhancements that you should buy as soon as possible, such as the various herbalism skills, but these are for after this first fight IMO. Others can wait even longer.

I bring both steel Strong, and steel Group up to level 3 ~ fast isn't needed yet (and silver is perhaps better for Fast?) and then max out stats. Signs I left relatively weak until near the end, when I maxed out those I found most useful.
Potions, with secondary characteristics, oils and the correct choice (steel/silver) are very useful. I never used bombs at all, so don't know whether they are worth playing with.... they aren't available this early anyway..

If in doubt, use the fact that you can regenerate while *most* monsters don't to string along a fight until you wear each one down. I preferred to stand and fight when possible, but backs to the corner helps protect you from 'back-biting' damage in that case... or getting where only a single opponent can reach at a time...

If you can damage with all three styles, then mixing them can be effective. use the hot-keys to inflict pain, bleeding and fear on enemies - reducing their ability to fight back.

If you find that you cannot damage using your swords, you can always try a 'torch'. This ignores armour, but does limited amounts of damage (it can also set inflammable enemies on fire)... sometimes this is the *best* weapon, usually just a 'reasonable' alternative. Cannot be used with your sword fighting styles/bonuses, so less of a good option in more difficult fights.