The white and yellow stuff on the soil are a combination of fungal growth and slime mould, likely caused by the soil in the pot being too wet for too long. The yellow growth appears to be an early stage Fuligo septica, common name dog's vomit slime mould, more info here https://wimastergardener.org/article/dog-vomit-slime-mold-fuligo-septica/. These types of growth occur on soil which has wood debris within it, but only if the soil/woody content is very wet. Neither of these will trouble the plant growing in the soil, but the soil being too wet all the time will cause some problems for the plant.
Allow the soil to dry out a little and don't keep it so wet; as the soil dries, these growths will disappear. Hopefully there is drainage in the pot in the form of holes at the base - check these are open and working properly so that water can get out. If there are no drainage holes, find a pot which does have holes and move into that. If you have the pot standing in a tray, remove that so the plant is not left sitting in water.
You mention ants; if you mean ants on the plant itself, they are likely there to harvest honeydew from either scale or aphid infestation - get rid of those and the ants will disappear. Whilst ants can and do make their nests inside pots, it is unlikely in this case because the soil is too wet - ants like much drier conditions.