The particles 「と」「ば」「たら」「なら」are the almost same function and the core meaning is "if". 「人に合わせないと不安」 means "I am uneasy if I go a different way from people." This is the answer of you!! https://japanese.stackexchange.com/a/1784/38911
– Mitsutoshi WatanabeMay 28 '20 at 12:32
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Does this answer your question? [Differences among -たら、なら、-んだったら、-えば, etc](https://japanese.stackexchange.com/questions/393/differences-among-%e3%81%9f%e3%82%89-%e3%81%aa%e3%82%89-%e3%82%93%e3%81%a0%e3%81%a3%e3%81%9f%e3%82%89-%e3%81%88%e3%81%b0-etc)
– jarmanso7Jul 16 '20 at 11:29