To indicate that some action is mandatory we use “must”/“have to” phrase in English.
e.g. “He has to complete it today”; “you must follow rules” etc.

In Marathi sentence formation is :

By “form of आवे (Ave) as per gender” we mean depending on gender and multiplicity of object the suffix will change as per आ-ई-ए-ए-या-ई (A-I-e-e-yA-I) rule
आवा-आवी-आवे-आवे-आव्या-आवी (AvA-AvI-Ave-Ave-AvyA-AvI)
e.g. for verb जाणे(jANe) form will be

Masculine singular जावा (jAvA)             Masculine plural जावे (jAve)
Feminine singular जावी (jAvI)                Feminine plural जाव्या (jAvyA)
Neuter singular जावे (jAve)                    Neuter plural जावी (jAvI)

The similar sentence in different tenses:

He has to do it(neuter) every day: त्याला हे रोज करायला / करावे लागते (tyAlA he roj karAyalA / karAve lAgate )
He will have to do it(neuter) every day: त्याला हे रोज करायला / करावे लागेल(tyAlA he roj karAyalA / karAve lAgel )
He had to do it(neuter) every day: त्याला हे रोज करायला / करावे लागले(tyAlA he roj karAyalA / karAve lAgale )

She has to eat mango: तीला आंबा खायला/खावा लागतो (tIlA AMbA khAyalA/khAvA lAgato)
She will have to eat mango:  तीला आंबा खायला/खावा लागेल (tIlA AMbA khAyalA/khAvA lAgel )
She had to eat mango: तीला आंबा खायला/खावा लागला (tIlA AMbA khAyalA/khAvA lAgalA )

Similar sentence but different gender and multiplicity of object:

Masculine
She has to eat mango: तीला आंबा खायला/खावा लागतो (tIlA AMbA khAyalA/khAvA lAgato)
She has to eat mangos: तीला आंबे खायला/खावे लागतात (tIlA AMbe khAyalA/khAve lAgatAt)

Feminine
She has to eat tamarind: तीला चिंच खायला/खावी लागते (tIlA chiMch khAyalA/khAvI lAgate )
She has to eat tamarinds: तीला चिंचा खायला/खाव्या लागतात (tIlA chiMchA khAyalA/khAvyA lAgatAt)

Neuter
She has to eat medicine: तीला औषध खायला/खावे लागते (tIlA auShadh khAyalA/khAve lAgate )
She has to eat medicines: तीला औषधे खायला/खावी लागतात(tIlA auShadhe khAyalA/khAvI lAgatAt)

For अकर्मक verbs which do not need the object, verb form will be created as per neuter-singular form.
I have to go: मला जावे लागते ( malA jAve lAgate )
We have to speak: आम्हाला बोलावे लागते (AmhAlA bolAve lAgate )

Try creating sentences with different verbs using above rules. Crosscheck them by creating same by “verb forms” feature on https://learnmarathiwithkaushik.com/