Thank you, Annet, for the file.
The YouTube link you have mentioned is something I have done many times, but it requires that the Figure was rigged with the Mixamo Rig, not with the Advanced BiPed setup. This tip states this clearly, but the Asset Browser does not at all, and I think that causes the problems for you. Sorry about that.
If you call up the Male Figure newly, go to the Layer Browser and click on every red Lock that you see. Then fine the Subdivision Surface and drag that group out of the Character. Uncheck the Skin Object, and delete all the weight tags.
Now you can apply the Character Maximo object, as in your YouTube link (Jonas Pilz’s tutorial). With that, you can apply all the MoCap data that fits the Joint rig.
Alternative
Would you mind checking out this tutorial:
https://youtu.be/sUkRFEQGTqU?t=7260
He starts it in this tutorial, You might check out his bird example as well, but the full setup of the walk cycle is then here:
https://youtu.be/Co2hPxJhgT4?t=2754
You need to use the IK controller to configure this hub.
The Add walk-cycle in the Male Character has some problems; I need time to file a report, as it is not clear right now why it produces all these problems.
All the best