Is Juma ki nawaz farz for Air Force trainees who cannot leave the camp to offer Juma salat?

Assalamuelekum I want to know about Juma ki Nawaz. I am living in Chennai. Earlier I was serving in Indian Air Force. At Air Force Camp it is training centre and there are more than 80 Muslim Trainees, who have been provided One big room for praying Salat. from last 20 yrs they were offering salat of Juma also inside Air Force camp. But All five time prayer is not regular in that room with Imam. These Air force trainees also can not go out of gate for offering salat of juma. Now my question is that whether Juma ki nawaj is farz on them,because due to restriction of Militry Service they can not go out in city and offer Juma salt.What they can offer Juma salat inside the camp or there any restriction according to Shariet and Islam, Or Zohar Nawaz is better for them .I approched the Local Mufti also Who is also from Darululoom Deoband, he says you ask this to Darool uloom Deoband it will be better, So Hazarat it is my request what is Fatwa says for these people,