Yes, you can connect multiple ad accounts from one network.

Step 1: Click on the profile icon in the bottom left-hand corner and select Accounts.

Step 2: To add another account, click the Connect button above the Accounts table.

Step 3: Select a network.

Step 4: From there enter your credentials, accept permissions, then select which accounts you'd like to bring into AdStage.

Step 5: Your account will now be going through its initial sync. Find more details on initial syncs here.