If you've gone through all the usual permissions but find that you still can't install the app then you might need to add RSC(Resource specific consent).
Now, you(like any good security conscious user) may be asking what is RSC and why do I have to add it. Well, it's a good question so let's try to answer it.
What is RSC?
Resource-specific consent (RSC) is an authorization framework built by Microsoft Teams and Microsoft identity platform that allows for granting scoped access to an app. What that means in English: It's a way in which to control what information an app can access.
If this is disabled, why do we need this?
Well, for many corporates, Microsoft will default to the more restrictive option so that it has to be explicitly enabled. Essentially, this allows owners of groups(or teams) to be able to consent fro their own groups. Since the app is installed to the team they create, they will need the ability to consent to the app being added. You can read more here:
How do I enable this then?
You need to "Configure group owner consent settings for RSC in a team using the Azure AD portal" or you can follow the instructions from Microsoft here. Bear in mind that Microsoft often changes their documentation, so the link may be a little different but the principle of what you are trying to do is the same..
TLDR:
You would need to enable Group owners to consent for their own group(last option for second section: i.e. Allow group owner consent for all group owners :
If you have the correct permissions in azure, then this setting can be found in the azure portal under:
Azure Active Directory > Enterprise applications > Consent and permissions > User consent settings.
Or use this link: https://portal.azure.com/#blade/Microsoft_AAD_IAM/ConsentPoliciesMenuBlade/UserSettings
This setting may take some time before it takes effect, then you should be able to continue with installation.
We hope this helps :)