The error messages are stating that specified logins are unable to connect to the associated servers.
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In the case of the maintenance user login failures:
- have you verified the DSI connection has been configured with the correct password for the given maintenance user login? (have you tried to log in directly to the specified servers as the maintenance user with the correct password?)
- have you verified the maintenance user login is not locked in the specified server(s)?
- have you verified the maintenance user login is configured in the target database as either a) a user or b) an alias to the dbo?
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In the case of the subscription failures I'm going to assume the login you're using ('sa') has a different password in the repserver and dataserver.
The login you use to create subscriptions should have the same name and password in the PDS, PRS and RRS (and ideally the RDS, too).
In most environments I've worked the decision was made to create a login specifically for managing subscriptions (eg, 'rs_admin'); this login is then created in all ASEs and RSs with the same password. All subscription activity (and might as well use for repdefs, too) is then performed with this login.
See the Repserver Admin Guide > Manage Replication Server Security; for subscription related issues see the section titled "Replication Server Object Creation Dependencies".