Make sure you have the latest published version of Admin Tools 6 installed on your Joomla 3 site.
DO NOT uninstall or unpublish Admin Tools on your Joomla 3 site, even if Joomla (erroneously, because of bugs I have reported over two years ago and never got fixed!) reports Admin Tools as being "incompatible" with Joomla 4. Joomla is lying.
Do whatever else you need to do to upgrade to Joomla 4.
After the upgrade go to System, Update, Extensions and click on Find Updates. You will see an update available to Admin Tools 7. Select it and install it.
Afterwards, go to Components, Admin Tools for Joomla, Web Application Firewall, Configure WAF and click on the Save & Close button. If you get an error, click on it again a second time.
That's pretty much all there is to it.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!