I was having this issue the other day and I for the life of me couldn't work out what was wrong.
I figured out that it was because Minecraft Marketplace is only currently available for the Bedrock version of Minecraft ([source|https://help.minecraft.net/hc/en-us/articles/360035347351-Marketplace-FAQs)] and I only had the Java Edition installed. When you click on "GET THIS ITEM", you notice that it redirects you to a webpage with a URL that is essentially trying to open up a store on a different client – this would be the Minecraft app for Windows 10 (or whichever operating system you were trying to open it on) which runs the Bedrock version. The link fails to redirect you anywhere if you don't have the Minecraft app from the Microsoft Store (Bedrock).
I bought the app from the Microsoft Store and then tried to purchase the Star Wars Mash-Up again, and the "GET THIS ITEM" link opened up the newly downloaded Minecraft app perfectly. I then had to purchase it from Minecraft Marketplace on the app.
Talita Frost
I was having this issue the other day and I for the life of me couldn't work out what was wrong.
I figured out that it was because Minecraft Marketplace is only currently available for the Bedrock version of Minecraft ([source|https://help.minecraft.net/hc/en-us/articles/360035347351-Marketplace-FAQs)] and I only had the Java Edition installed. When you click on "GET THIS ITEM", you notice that it redirects you to a webpage with a URL that is essentially trying to open up a store on a different client – this would be the Minecraft app for Windows 10 (or whichever operating system you were trying to open it on) which runs the Bedrock version. The link fails to redirect you anywhere if you don't have the Minecraft app from the Microsoft Store (Bedrock).
I bought the app from the Microsoft Store and then tried to purchase the Star Wars Mash-Up again, and the "GET THIS ITEM" link opened up the newly downloaded Minecraft app perfectly. I then had to purchase it from Minecraft Marketplace on the app.
Hope this helps.