Good morning, I would like to read some recommendation, since what happens is that within my company it is expected to be able to join 3 different lines of 300mb each and with a mikrotik team, the thing is that I do not know too much about the balancing and I wanted to see they could Recommend some equipment and / or technique to carry out this section.

If not a bot, please provide a network diagram..........

sum of different ISP lines

DO NOT EXIST

Except if the 3 lines are of the same provider, and the provider also join the lines at the start (bonding or similar).

You can only do approximative "balancing" and sparse the connection between lines, but max speed for single connection still 300Mbp/s.
You can use 3 distinct connection, one for each line, to reach 900Mbp/s downloading a file at diverse start point, like with GetRight or similar.

In this one, the 3 lines are from the same tester, what happens is that this project has only given me access to one case and they only asked me to investigate close to this sum, but I don't know much about the subject, if you need a diagram of red with pleasure I can do a do it and if a cone of technique arrives for the solution of my problem, please I hope you can explain me :3