The installer was initially trying to work around the “D:” partition. You created that “for Linux” but it knows it for what it is, a Windows partition, probably even already formatted NTFS. Since you don’t have anything on that partition, just delete it in Windows beforehand. Now you’ll have 23GB of unallocated space for the SuSE installer to work with.
Keep in mind that the installer can only make an educated guess. You can try a couple of its guesses, or go into expert mode and set up the partitions yourself. A typical approach would be to make the 2nd primary partition “swap” sized ~1.5GB. The 3rd primary would be the root partition, designated with a “/” (forward slash), ~8GB. The remaining partition would be for “/home”, ~13GB.
As Larry explained, the installer may propose/you may choose to use an “extended” primary. This is done to allow for the addition of more partitions than 4. You could make the 2nd the extended, in which case swap, /, and /home would all be on “logical” (the term for a partition within an extended) partitions. Or you could make swap a primary, / a primary, and then make the 4th an extended, with /home therefore being on the first logical. Having said all that, with this smaller drive it is unlikely you will have a need for another partition, so you may just want to go with 4 primaries (i.e., no extended at all) and be done with it.
If you do the setup manually, you only need be concerned with a 3 fields of data to enter. Click the “Format” box, and under the File System tab, choose ext3 (or “swap” for, well, swap). In the “Start” field enter the size, e.g., “8GB”. In the “Mount Point” field, for the swap partition leave it blank, for the root partition enter the forward slash (/), for the home partition enter “/home” (forward slash/home). For the last partition you enter, leave the start/end fields as already filled in, which will take the remaining space exactly. When done, check that the summary is displaying what you meant to enter. (If you choose to use an extended, you’ll need to tell the partitioner that, too.)
Having storage on the other drives for shared use between Windows and SuSE is fine. You’ll want to give some thought to how you want the partitions on those drives organized - it’s better to have manageable sized partitions which align with a particular function. One big 250GB partition for data, photos, video, editing, compiling, etc. is common, but not a particularly good idea. Cross this bridge after installation.
One last nit: Best to stop thinking in terms of drive letters. Windows arbitrarily assigns those, but they are meaningless other than to differentiate one from another. They are not even drive assignments; they are partitions. They need not be sequential, and can easily not be in the actual physical sequence in the machine. All this is a relic from DOS. In Linux, partitions are assigned the number they have in the partition table, and are mounted at a directory point (i.e., a folder) which are named however makes it easy for the user (e.g., “/home/video”). In Windows you can use the drive label to identify a partition similarly. Just fwiw . . .