The old Jar file for skyrising skyblock did not require a world type to be set in the newer versions, because of this the world type is set to default, as this version requires you to have the world type set to skyblock for it to work you cannot update old worlds to 1.17 yet. just create new ones

You can convert your world generation type. First, back up the world folder. Then you can use a NBT editor (such as NBTExplorer) to change to generation type.

Open level.dat in the world folder root and under

Data->WorldGenSettings->dimensions->[All three dimensions]->generator

change type: minecraft:noise to type: minecraft:skyblock.

This should work for both singleplayer and server worlds, but with server worlds also change the server.properties file to have level-type=skyblock.
If done correctly, all new chunks should be generated under the skyblock generation for this mod rather than using the default generation.

Thank you!