Three common causes, in the order worth checking.

The connection. A slow or unstable connection is the usual one. Try again on a fast Wi-Fi network and download or update one map at a time. The download will normally complete in the end, but it can take a long time on a poor connection.

Not enough storage. Free up space by removing other apps or files, or by deleting maps for countries you no longer need. The Offline Maps panel shows your storage location and the free space on it.

The app lost access to storage. We have seen this after system updates. Clearing the app storage sorts it — see the full app reset answer, and be aware that it erases your settings.

One rarer case: if you have chosen an SD card for map storage and DMD2 loses access to the card, downloads will not proceed. Make sure the card is inserted and readable. We do not recommend SD cards for map storage — they are the most fragile part of the chain.

If a queue has got itself stuck, Cancel All Downloads at the top of the map browser stops the running download and clears the rest in one tap. Partly downloaded files are discarded; maps already on the device are untouched.

Finally, if you are on the free tier and nothing starts at all, check how many maps you already have. Without a license you can keep three maps on the device at a time. Deleting one frees a slot.