Architect - industrial building and interior visualization

I have files from a previous "architect" who got disabling sick and could not continue with this task. He left .dae and .pln files, but i don't know for which software using them. I need help with designing mostly factory interior and people. I'm super busy with other stuff so this job will develop in burst now and then when i have time to spend on it. Im on a tight budget, so a low hourly fee is apricated.