Better clear up things with your employer/sponsor. If they have done the requirements on their side of the process... requirements as certified employer, market testing, etc... then the next is to submit your visa application... usually the employer has an agency that does this or you can file on your own. Visa fees are are published in the DoHA website... 4,045 is for the primary applicant, + half of that for partner and + 1/4 for any dependent below 18 [child(ren)].
So things to clarify:
Has the employer/sponsor made the necessary steps toward being a sponsor
Does 80% of processing fees include visa fees or only processing fees of migration agent
Prepare your documents, TOR, Diploma, Employment Certificates, pay slips, passport, etc. Depending on occupation and ENS visa scheme, you may need English competency results and to undergo skills assessment.
More info about ENS Visa can be found here.
https://immi.homeaffairs.gov.au/visas/getting-a-visa/visa-listing/employer-nomination-scheme-186