I am working on a new office 365 tenant, and the tenant already has a root site collection of type "Classic Team site" created for us. but a sharepoint admin (who is also the root site admin), reported that when he tried to add an "Embed Code" inside a classic page on the root site, he got this error message:-
This HTML cannot be inserted because you don't have access to add scriptable Web Parts in this site. Please contact your administrator if you think you should have rights to do so.
Now which checkbox i need to "Allow", to allow the sharepoint admin to add custom script inside the root site?. As i know and as mentioned on this documentation Allow or prevent custom script, that "Root site" is considered as a Self-Service site, so can i say that i only need to "Allow" custom script on Self-Service while i can leave it disabled on Personal Sites, to fix our problem of not being able to add custom script on the root site?