How do I migrate from HUB Plus Library to Greyscalegorilla Studio?

As a Cinema 4D user you can work with HUB and Studio simultaneously.

You can see the comparison of HUB and Studio from this link.
Studio includes materials and assets (Models, HDRIs, Gobos, Bokehs, Surface Imperfections and Area Light Maps)
HUB includes materials, assets and the plugins.

Important Notes:

HUB > Plus Library assets are not compatible with Studio.
HUB > Plus Library assets folder cannot be used with Studio.
For Studio you need to download the assets again when you need to use them.
Studio requires its own assets folder and assets.
Make sure you set a different folder and this folder should not be inside HUB assets folder.
While you can download materials as collection packs via HUB, Studio only allows individual downloads of assets which provides instant access to any asset.

HUB only content:

Procedural materials: Car paint, neon, some glass and liquid materials are exclusive to HUB Plus Library. They will be added to the Studio in future updates.
HUB Plugins:
To continue using Greyscalegorilla plugins you need to keep the HUB installed.

If you want to free up some space in your harddrive you can follow this guide to remove collections.
Please follow this installation guide for Greyscalegorilla Studio - Cinema 4D

Relinking Assets

HUB Plus Library and Studio assets have different naming convention. And that prevents bulk relinking. You can replace one by one or re-assign over the old assets from Studio.

- HDRI example:

GSG_PRO_STUDIOS_METAL_002.exr (HUB)

GSG_HC006_A002_GSGPROSTUDIOSMETAL002.exr (Studio)

- Material example: "C Gold Polished” from EMC collection

C_Gold_Polished_DIFF.jpg (HUB)

GSG_MC001_A171_CGoldPolished_4k_basecolor.jpg (Studio)

C_Gold_Polished_METAL.jpg (HUB)

GSG_MC001_A171_CGoldPolished_4k_metallic.jpg (Studio)

C_Gold_Polished_NORM_OGL.jpg (HUB)

GSG_MC001_A171_CGoldPolished_4k_normal.jpg (Studio)

C_Gold_Polished_ROUGH.jpg (HUB)

GSG_MC001_A171_CGoldPolished_4k_roughness.jpg (Studio)

Project Asset Inspector - showing missing assets from HUB

RS Asset Manager - showing missing assets from HUB

Right-click > “Replace Files With” works however requires selecting each asset one by one.

This workflow is exact same for Project Asset Inspector, Octane Texture Manager and Arnold Asset/Tx Manager.

*Right-click > “Relink Files” doesn’t work because C4D looks for exact same file names.

RS Asset Manager - after assets manually relinked.