H1B, H4 Visa

Today (01/16/2020) at 9:30am I had my H1B extension interview at Mumbai and I was issued 221g Yellow slip requesting for additional documents to be submitted through email. This is how the interview went:

VO: Good morning, how are you today ?
Me: good, how are you?
VO: good, thank you. Passports please
Me: *proceeds to give passports and I797*
VO: only passports please.
VO: *pulls up my application and starts discussing something her colleague next to her*
VO: Is this new H1B or extension ?
Me: extension
VO: who is your petitioner ?
Me: *Answers*
VO: will you be working with your employer?
Me: No, I will be working for my client YYYY company
VO: what is the location ?
Me: *Answers*
VO: what is your salary ?
Me:*Answers*
VO: *hands me a small 221(g) yellow slip* Sorry, we are unable to issue at this moment as we require additional documents, please refer to the slip for next steps
Me: what is the process ? Do I need to come back again?
VO: you will need to send the documents mentioned on the slip to us, once approved we will notify you about the next step which will be dropping your passports at the Dropbox.
VO: meanwhile do you the rules and regulations as an employee in the United States ?
Me: Yes
VO: *hands me the know your rights paper*ok, enjoy your stay in the US and these are your DOs and DON'Ts during your stay. Have a great day
Me: thanks, you too

I don't understand why I was issued the yellow slip. I had all the documents which are required to sent through email at the interview
Why didn't the VO ask for these documents?
And how long would it take after submitting these documents to get a call by consulate to go to Dropbox

The documents which are asked to send through email are:
1) I-129 and LCA
2) client letter
3) contract between employer and client
4) contract between employee and employer

And also, do I need to send these documents to the given email ID ([email protected]) or my employer has to send them ?

Please help