Windows 98 as far as I can remember came in two parts one floppy disk and one CD.
The floppy was the startup disk.
I think the later versions Windows 98SE may just have been on CD.
The startup disk and the ISO are available on the net.
I understand that there is a floppy disk version on Windows 98 which is/was available from MS but was 39 Disks.
There seem to be plenty of second hand internal IDE CD readers on various websites.
Best of luck,