Cannot enable cookies in Safari

Is there a specific problem? You have presumably enabled cookies in iPad Safari settings?

Settings > Safari > [Privacy & Security] Block All Cookies - set to OFF

Be aware that in common with many security-focussed browsers, iPadOS14 Safari will continue to block third-party cookies by default. This behaviour is an element of ITP (Intelligent Tracking Protection) - this being a significant enhanced privacy feature of the OS.

Some websites are still clinging resolutely to using third-party cookies or other tracking technologies - either for their own function - or for lucrative advertising opportunities. Unless these operators move-on from these practices, they will eventually die.

This not just a Safari issue. I have this issue with chrome as well. It makes it hard for students doing virtual learning if third party cookies are blocked by default.