If the linoleum is well adhered, many times it is possible to tile over the existing flooring.
If not, I would suggest scraping it clean and make sure it is well leveled, if necessary use some leveling compound.
Since I'm not a pro, take this as just opinion, but I would guess you do not need to seal it in any way, just use your mortar to anchor the tiles. Perhaps dampen the existing concrete to prevent it from soaking up moisture from the mortar and preventing it from sticking well to the cement and setting up as strong as possible.
I remodeled an office that had commercial Armstrong Vinyl. I removed the floor by heating and tearing it up, then I used a black metal-oxide wheel in my drill and ground the remaining rough glue down. After I got the floor usable, I applied a floor leveler compound to give me a solid surface to work with, then I installed the tile. No return calls for popped tiles, and the shop owner was quite pleased with how thorough I was in the prep work. It's been about 2 years since that install. Very heavily trafficked reception area of a busy auto shop.