Any of 2.5" SATA SSD should be supported with your Vostro 15 3568.  You can select brands, capacity, cost, depending on your preference usage, budget, and market availability.  Some examples can be found at this big shopping site.

Use the service manual for drive replacement instructions https://www.dell.com/support/manuals/en-bb/vostro-15-3568-laptop/dell_vostro15_3568/removing-the-hard-drive-assembly?guid=guid-1e2ca1c4-dfc5-4d21-a75e-cf260721090b&lang=en-us