I don't know what that filler is - but - you can use almost any kind of paint. Understand that it won't be exactly like the rest of the wall.

First, clean it up and get rid of the more obvious lumps.

Then use a good primer - Kilz is one of them but there are others.

After that is good and dry, apply your top coat. To help it blend in somewhat with the existing paint, use your brush to lightly feather it into the old paint. The paint that you use should be the same as the old paint - that is, whether it's oil-based or latex and whether it's flat or semi-gloss.

Good luck!

Kilz is king

It looks like your half-assed contractors should have used white stucco as a filler instead of whatever that is. If you do use kilz to turn it white be sure to buy exterior grade kilz, not the red label can.

Right on, brother! (Or sister.....)

Whoever filled that is a right joker. What a crappy job. First I would take a sharp edge and trim the inner edge where the doorframe and wall meet. Then get to sanding and it might come closer to being flat. You might even be able to get the outer corner to run almost in a straight line. Then get some external undercoat/primer, paint it on with a slight overlap of not the old paint, then white outer coat; do you know what kind of paint that is by any chance?

Sadly no. Really hoping it's the most common type - whatever that works out to be.

Good grief. Agree with others that you need to sand/scrape that down at least. The bulge at the bottom where it slumped is ugly and looks dodgy, and the lack of flexible exterior caulking between the door trim and the wall is not going to weather well. You can get small patch batches of stucco at the hardware store, that should be a suitable base for any exterior paint. Finally, put a small potted plant in front of it when you're done, because you'll need it.

Well, once you are done sanding and have cleaned the dust off, don’t forget to tape the doorframe and floor with some masking tape, leave it there once primer dries, then put your topcoat on, might want to “feather” the edge between new paint and old paint so there’s no hard line between the two, wait for that to be touch dry and THEN remove the masking tape. Much easier than trying to clean up paint drips and spatters after the fact.