Dokucraft, The Saga Continues (TSC) assets are made by the community, and every contributor decides what their assets can and can't be used for. If an asset is contributed to TSC, the only base requirements added onto it is that it may be used in any resource packs on this website and derivative works of it may be created by other contributors if it is for TSC.
This means that we, as a group, can't just give people permission to use most things in the pack for whatever they want. If you want to use a TSC asset for something that is not strictly private, you will have to ask whoever made it.
An exception to this rule exists for anything directly from the original Dokucraft packs by Doku. When Doku discontinued the packs, he explained that all of the textures in them are free to use for anything.
If you have found an asset that you want to use and you're not sure who made it, feel free to ask in the #dokucraft channel in our Discord server.
If you want permission to use a lot of assets from the packs, just know that getting it might be a lot of work, just because they might be made by a lot of different people.
Everything above applies to all assets in the packs, see that first if you skipped right here.