It's really loud when the person who lives below me walks around their apartment because they walk on their heals.
When my neighbour downstairs walks, he walks on the back of his heals so it's really loud.
この場合、次のような言い方ができますよ。
ーIt's really loud when the person who lives below me walks around their apartment because they walk on their heals.
「アパートの下に住む人がかかとで歩くとすごくうるさい」
to walk on one's heals で「かかとで歩く」と言えます。
ーWhen my neighbour downstairs walks, he walks on the back of his heals so it's really loud.
下の階の隣人が歩く時、彼はかかとの後ろで歩くのですごくうるさい」
to walk on the back of one's heals とも言えます。
ご参考まで！
カナダ 
