If you don't see the "Get Add-Ins" button in Outlook when trying to install Oliv, try out the following scenarios and steps to fix it.
Scenario 1: Optional Connected Experiences is disabled
- Go to File -> Options --> General
- Click the "Privacy Settings" button.
- If the "Enable optional connected experiences" button is not checked, the 'Get Add-Ins' button (among other functions) will be greyed out. Check it.
- Restart Outlook and the "Get Add-Ins" button should be visible now.
Scenario 2: Account connection is misconfigured
Sometimes, the Outlook account is connected via IMAP / POP3 instead of a direct connection with the Exchange server. You need to sign out and then sign in with your credentials to connect the account again.
To check the connection type:
- Click the File tab. Click Account Settings, and then click Account Settings.
- On the E-mail tab, the list of accounts indicates the type of each account.
- It should like below. Check if your account is connected as "Microsoft Exchange" (the desired option).
- If it is connected as IMAP/POP/MAPI, sign out and sign back in with your Exchange / Office 365 credentials directly.
Scenario 3: Button was removed from ribbon accidentally
- Go to File -> Customize Ribbon
- If you see "Get Add-ins" on the left, create a group first by clicking on "New Group" and then move the "Get Add-ins" button to the right side.
Scenario 4: Admin has disabled third-party Add-Ins
Ask your Admin to sign into Office 365 with an admin account. They can then navigate to Admin center -> Settings -> Services -> User owned Apps and Services as the following picture shows and must enable both the options.