No matter what I try, with the Windows 10 GoG version of Sim City I get no high tech jobs. I have played this plenty of times before and have never had trouble before, so it's not like I don't know how. Does anybody know what could be the issue?

You need high education level and a high for for HT-industry. Watch the charts and look for desirability for HT-I. If you have green land then it's alright. But at standard taxes dirty industries and the manufacturing industries bring a big decrease for desirability. You have to get rid of it. Raise taxes and destroy them or start in a new zone and raise taxes right at the beginning or before you place industrial land zones. .