There's no minimum requirement of website traffic to get an account approved for adsense but you won't make much money without enough website traffic.
To make a little money from adsense you need to have at least 1,800 daily uniques to make around $20.00 to $40.00 per month with adsense.
I'm telling you that from experience from my own website.
When I had under 1,000 visitors I wasn't even getting any adsense clicks.
I would work on getting your website content built up and forget about Adsense while you're building up the content and website traffic.
You won't be earning much from Adsense anyway without the traffic. Once you start getting 1,800 unique visitors per day then you should see a little money coming into your adsense account.
You do need at least 7,000 daily uniques to earn $600.00 or more from adsense so be prepared to work on building up content and traffic for a few years before you start getting good income from Adsense.
It takes time but in the end you should see some money.
I worked on one of my websites building up content and traffic for 5 years before I started earning enough income to quit my regular job.
Be prepared to stick it out because years down the road you should reap the rewards from all your hard work on your website and then your blog or other website will likely be making lots of income on autopilot while you're asleep or away on vacation.
I do still have to work on my blog adding some content at least a few times per week just to keep my search engine rankings by adding the fresh content but I don't have to work as hard as I used to and the money just keeps coming in.
I wake up in the morning there's money in my adsense account that I earned overnight.