You don't need to manually download the resource pack. It will automatically download once you login.
Some players experience trouble while downloading it, those players can get it here.
Be aware that your download will not update itself. You will have to redownload it every now and then to keep up with changes.
1. Download the AvatarMC Resource Pack
2. Add it to your Minecraft resourcepack folder
Once downloaded, add the file to your Minecraft resourcepack folder. If you have trouble finding it, please
follow the tutorial below. Otherwise skip and continue with step 3.
Now place the file in that folder without extracting it.
3. Open Minecraft and activate the resourcepack
After putting the resource pack into your resourcepack folder you now need to activate it.
Start Minecraft and click on Options, then on Resource packs and move the downloaded resource pack to the right side of the screen by hovering over them and clicking it.
As you can see, the resource pack is on the right side of the screen now which means that it is activated and ready to use.
Tip: Disable the server resource pack while creating the server bookmark in order to not get annoyed with in game downloads.