Yesterday we were installing PTE app on production environment and it throw an error as below.
We are juggled by seeing this message and thinking why it is showing an error message when we are uploading extension by using administrator login which is global administrator.
To overcome this error there is new permission set has been introduced in business central wave 1 2021
EXTEND. MGT. – ADMIN
You need to assign the above permission to install the app as below.
Hopefully this will help
Stay tuned for more.
Ammolh Saallvi Blog 
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