If you're starting out - which I'm assuming you are since NRC has you doing a 5k as a long run, then I would suggest following their programme.  Yes they're asking you to go at that 10 minute pace per KM although that's pretty much a walking pace.

I think these calculators are great as they provide objective paces for training.  But not at the beginner stage when you're still trying to get the aerobic fitness to run without taking breaks.

Also those paces are worthless unless they are used with properly designed workouts for what you're trying to achieve.

Go to instagram and search for @runrx to improve your posture and efficiency.

What speed do you use for the speed calculator?

Have you done a 5k time trial or a 10k time trial where when you finish you have nothing left in the tank? if so then that speed should be correct.  If it's not an all out time then it's probably too slow.  If you can talk easily at 8mins/k then that's your easy pace.  I personally use the following pace calculator in conjunction with Jack Daniels' workouts.

https://runsmartproject.com/calculator/

A lot of people here say you have to run easy and that's true - but the real reason you run easy is so that you can run more.  You take it easy so that you increase your mileage, take less rest days while at the same time keeping the risk of injury low. As a beginner, you should focus on building a base level of fitness - which basically means getting comfortable enough with a level of mileage.  There's also nothing wrong with doing things like strides - 20second sprints followed by 1 min rest at the end of my easy runs.  If you're only doing 10km a week, then in my opinion you should focus on increasing your weekly mileage.  Run easily more frequently and the speed will come as you become fitter.  Doing long runs and speed training is not going to help much if you need 2 or 3 days to recover from them.

Having said that, I'm still a novice with 2 years of running under my belt so I still have a lot to learn.  I did 4 HMs last year, the last one being the Penang Bridge HM.  I hated the traffic jams in that race but managed to finished in under 2:30 training with very little training the month before the race ( although strava tells me i did 1033km in 2019).  With no races this year, my goals this year are to increase my mileage to 50km a week consistently and to go from 27min 5k to 25min and eventually get the fitness to go sub 2hrs in the HM distance.

If you're just starting out consistency is probably the most important part about running - that means actually getting out and running.  Don't worry about distance and definitely don't worry about pace.  I feel for a beginner, 1 hour a day of running is actually a lot.  There's no point in doing 1 hour runs if you need 2 or 3 days to recover... 30-35 mins a day is a good amount but try to increase the number of runs you do a week.  A weekend long run is actually very beneficial - 20-25% of weekly mileage is about right for a long run so this can be your hour long run.

For comparison, right now my mileage is about 35-40km a week and most of my workouts are between 40-50 minutes a session and I run 5-6 times a week depending on my schedule and how I feel.  It's not too much stress but at the same time good enough to feel (and measure) the improvements in my fitness.