I'm by no means an expert in this field and not sure if I understand what you need, but as I understand it to get it to work you have to go through 2 steps.
- Register an app and make sure the FME has permission to use the app.
- Make sure the user is allowed to access the data.
You say "Moreover, when trying to identify with my personnel Azure account, it says that the approbation from an admin is required, so that FME can access the resources."
This feels for me like FME is not allowed to use your registered app. (Step 4)
About the need to log on, you always have to log in with an account to create the connection in FME. This is the second step. This way you make sure the user is allowed to access the data on the sharepoint site. This way you can take away someone's access without to having to change a "general" login. This is by design.
I think you can work around this by creating a web connection and share this web connection with other users. They then can use your account to access the data on Sharepoint. Note that this is bad advise as it defeats the possibility to retract data access from an individual. (Which is needed when someone quits his current job.)
Thansk for your answer!
Regarding the FME software that may not be allowed to use the registered app: do you know how it would be possible to allow FME on our AzureAD with a a certificate, rather than a client ID? This option has been asked by one of my IT colleague, but we don't know how to do that.
Here is a screenshot of the current configuration, as described in the FME documentation.