Mrsjones, maybe you meant to submit this under Tagalog and not English.
Bakit hindi instagram? = Why not instagram? (Why use something else and not instagram?)
Bakit hindi ka mag-instagram? = Why not instagram? (Why not join/use instagram?)
a: why don't you create an instagram account?
a: bakit hindi ka mag-create ng instagram account?
b: i don't want to, not one more password to keep.
b: ayoko, kasi isa na namang password ‘yun para tandaan = I don’t want to because that would be another password to remember. – this is how we would say it.
a: come on, just create it.
a: sige na, mag-create ka lang. OR sige na, i-create mo lang.
b: i don't want to.
b: ayoko
b: ayoko nga e = I said, I don’t want to
a: come on, just instagram.
a: sige na, instagram lang
b: stop pestering me!
b: tigilan mo ang pangungulit sa akin!
b: huwag mo nga akong kulitin! = please don’t pester me! – this would sound more natural