Hello,

The eligibility criteria for the course through regular entry will be

Eligibility for those who cleared class 12 or equivalent in 2019 or earlier:

• The candidate must have  Mathematics and English in class 10.
• They should have cleared class 12 or equivalent in 2019 or earlier

Eligibility for those who cleared class 12 or equivalent in 2020 or 2021:

• The candidate must have s Mathematics and English in class 10
• They should have cleared class 12 or equivalent in 2020 or 2021.
• The candidate should be:
  (i) currently enrolled / previously enrolled in any Bachelor's Degree program in campus mode.
  (ii) completed 1 year (campus mode only) diploma
  (iii) completed CA Inter

As you are in 12th you are not eligible this year but you can apply for it next year.

Application process

• Anyone who meets the eligibility requirements can apply by completing the application form, submitting the relevant papers, and paying the application fees.
• The Qualifier Process will be required of all Regular Entry candidates. The average of the top three out of four assignment scores will be computed in each course. Only those who receive the requisite minimum average assignment scores in all four courses will be permitted to take the Qualifier Exam.
• 
  Only applicants who get minimum required average assignment scores in all four courses will be eligible for the in-person invigilated Qualifier Exam conducted at the end of 4 weeks of coursework. Only these candidates will receive hall tickets.
• Only those who pass the Qualifier Exam will be eligible to register for Foundational Level courses.

Go through the official website and you can see all the procedures

https://onlinedegree.iitm.ac.in/admissions.html#AD5

Hope it helped

Thank you