How to revert back from Studio 2021 to Studio 2017

Dear all,

Today my computer restarted and I couldn't use Studio 2017 anymore.
Well, I started to use Studio 2021 as advised before but it doesn't let me
add Google Cloud translation API anymore. Normally
I translate 1800-2000 characters per hour but with the API 
I translate 6000 characters per hour because I only have to edit the AT.
I have a huge translation on my hands and I have to finish it by tomorrow.
Please, how could I revert back to Studio 2017? I need to use this
API, otherwise I will translate the text for more 3-4 days. 
I wasn't aware of the fact that I would lose this most helpful API
with new Studio. If I had known it, I would never have upgraded...
It slows down my speed by 3 times. 
Could anybody help me? When I just tried to use the new 
license for Studio 2017, the programme did not accept it.
Thank you in advance,
Maarja