Try this test. Take a trigger spray bottle (Windex bottle or the like) and wet a small area of the paste. Then put a peice of paper toweling over the wetted paste and soak it with the sprayer. Keep the toweling wet for at least 20 minutes, then romove the toweling and draw a small taping knife or putty knife over the wetted paste. If the paste comes off with the knife, then you'll need to remove all the paste before painting or texturing the wall.
I remove adhesives by spraying water and TSP with a garden type compression sprayer, keeping the paste wet several minutes, long enough to be able to draw a 6" taping knife over the wall and take most of the paste off. Washing the wall afterwards with clear water and changing the water in the bucket often. I try to be sure to remove as much of the residue as possible. I can wash the paste off the walls in a 13x15 bedroom in an afternoon.
If you find that the test leaves the paste unsoftened, then prime the wall with a stain killing type alkyd primer before you attempt to apply texture.
Here's the catch, even with a stain killing primer, if the paste can be softened, it will soften with the texture which is water based and takes longer to dry than a normal paint. If the paste softens, you must remove it.