When i tried to add a new user to an access point in the access list i am getting an error when i try to save' other config or software upgrade is blocking auto sync. Devices will be automatically uploaded after the blocking job is completed
Auto sync jobs will be having error if any other configuration or software update job is running as at any point of only one job can run.
That yellow pop-up message is just a warning that there will be a delay before the changed settings are live on devices. As KR mentioned this is because only a single job is allowed to run at a time.
Normally configuration changes are pushed immediately to devices but if a blocking job is long-running, like a software update job for many devices, it might take some time before devices are updated with the new settings.
The warning message is to let you know of this delay and isn't something to worry about unless you need the updated settings immediately. If you do need these settings to get pushed out immediatly, you could pause the blocking job and wait for the auto-sync job to be created automatically by cnMaestro and then resume the paused job after auto-sync completes.