DigiLens Process Integration Engineer interview questions

The hiring manager contacted me through one of the job hunting / recruiting website. Scheduled a phone interview. The phone interview went pretty well. The hiring manager then asked for my schedule in the next week and said he wanted to invite me for an onsite interview. I hadn't received the invitation in a week so I sent another email to follow up. No response from the hiring manager so I didn't bother to follow up again. I didn't really applied for this job, and was approached by them. I expected at least some respect to the candidates, not just even not wanting to reply a simple email.