Actually, you should AVOID Win10 v20.04 at this time -- as MS has been having SERIOUS problems with it and still have a bunch of issues they have not addressed and have provided no date to expect fixes.
You would probably do better going after Win10 v19.09 -- as that is stable and not encountering issues. Plus, the newer the Win10 version, the less likely it will work on older Win7 PCs.
IF you post in this forum when you're ready to do that download, someone can tell you where to find an ISO file -- but understand, you must upgrade from INSIDE win7 for the upgrade to be free -- as the upgrade tool has to see Win7 already installed and running on the PC.