Mainstay Medical interview questions

Unprofessional, I do not recommend applying to jobs at this small company. I applied online on Linkedin, and received an email from the HR person. It's the only company that made me do the interviews in person in the middle of the pandemic. First interview was with the HR who was overly friendly, then the second interview was with the hiring manager, who was rather cold, I did not feel a connection there. The HR completely ghosted me, even after I followed up over 3 times with him, how unprofessional? It's a very small startup, they have time for a short rejection email after meeting in person. If they don't have the decency to follow up with a few candidates after making them come interview in person, it's not worth working there.