Unable to download Star Wars Minecraft mash up pack

Hello There ! I would recommend checking this link Troubleshoot game or app installation problems on your Xbox console | Xbox Support for further help.

The one in that link is for the console version of the game. You would need to buy it for PC if it's available.

Bedrock edition of the game does not have those mash up packs. Only Minecraft Xbox One Edition had the mash-up packs, and that version can no longer be purchased on the Xbox. You might still be able to purchase a physical version of that game, whether you will still be able to get the mash-up packs for Xbox One Edition, I do not know.

The Starter collection includes the Minecraft base game and the Starter Pack compilation: Greek Mythology Mash-up, Plastic Texture Pack, Skin Pack 1, and Villains Skin Pack.

Minecraft for Windows 10 only includes the base game.

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today despite this Jonathan

I can advise you with few things, but if the issue persists you may need to reach minecraft support
https://help.minecraft.net/hc/en-us/requests/new

First, if you try deleting the add-on / using a world without it. Everything is working as expected?

If yes, can you double check if minecraft and iPadOS is up to date via app store?

If yes, can you try reinstalling the game? (don't forget to backup worlds if necessary)