What kinds of fonts are you trying to add and where are you adding them?
It's possible to upload fonts from your own collection into your Creative Cloud account using the Creative Cloud desktop app. Those fonts will appear in devices signed into your CC account, including an iPad. Just be sure the license to those fonts allows them to be uploaded.
The iPadOS does not make it easy to install new fonts. Individual font files can't be installed directly into the iPadOS. You have to go to the app store and buy font packages that are installed in the same manner as apps. I really do not like that approach. Adobe Fonts is a decent work-around since fonts can be added one at a time or as many as 20 at a time.